Students perception on "hard"

In ch1 of Talking about leaving on page 10 there is the following quote "In a study of 1,200 students taking Chemistry 116 at Purdue University, they found that the 'difficulty' of the class was very differently perceived by the students who took it, and by the faculty who taught it." My background in education has allowed me to witness this first hand. I taught Geometry to high school students. Mathematics, when I was in High School, had always come naturally to me. So when a student asked me if something was hard I would say no, however for the students grasping concepts in Geometry is something that is very hard. The students have to think in a new way contrary to what they have been previously taught in math classes.